The Effects of Septal Deviation, Concha Bullosa, and Their Combination on the Depth of Posterior Palatal Arch in Cone-Beam Computed Tomography

Statement of the Problem Nasal breathing is the major pattern of air intake. Changes in breathing pattern alter the posture of the head, jaws and tongue that could change pressure on the jaw and teeth and affect their growth. Purpose This study aimed to investigate the relationship between septal deviations (SD) per se and in combination with concha bullosa (CB) on maxilla; particularly the depth of palatal arch. Materials and Method This descriptive-comparative study was performed on 116 cone-beam computed tomography (CBCT) images. The images were categorized into four groups (n=29) as follows; group 1: SD+CB, group 2: only SD, group 3: neither SD nor CB, and group 4: only CB. In coronal images, deviated septal length (DSL), angle of deviated septal curve (DSCA), palatal arch depth (PAD), palatal interalveolar length (PIL), PAD/PIL ratio, septal vertical length (SVL), maxillopalatal arch angle (MPAA), interjugum distance (IJD), and jugum angle (JA) were measured. The data were statistically analyzed with Tukey's HSD and Chi-square tests. Results There were statistically significant differences in DSL and DSCA (p= 0.0001) among the four groups. The study groups were not statistically different regarding the IJD, JA, MPAA, PAD/PIL, PAD, PIL, and SVL. However, in group 1, PAD/PIL were significantly correlated with DSCA and DSL (p= 0.037, and p= 0.043, respectively). Conclusion Based on the findings of this study, simultaneous occurrence of SD and CB influenced the depth and curve of the palatal bone. The PAD/PIL ratio was negatively correlated with the DSCA angle. This correlation was associated with a decrease in PAD, indicating that concurrent occurrence of SD and CB remarkably affected the palatal base of maxilla.


Introduction
Nasal breathing is the primary mode of air intake that can be replaced by oral breathing due to obstructive or habitual causes. [1] Most common obstructive causes are hypertrophied adenoids, maxillary sinusitis, concha bullosa (CB), deviated nasal septum, and hypertrophied inferior concha, respectively. [2] The nasal septum is located in the medial wall of the nasal cavity. It extends from the roof to the floor of the nasal cavity. It lies between the cribriform plate and the hard palate superio-inferiorly. It also spreads from the septal cartilage anteriorly to the vomer and the perpendicular plate of the ethmoid bone posteriorly. Three projections in variable sizes called the inferior, middle, and superior nasal conchae form the lateral wall of the nasal cavity. Pneumatization of the concha, called concha bullosa (CB), is one of the most common variations of sinonasal structures. CB is most frequently found in the middle concha, [3] and in association with septal deviations (SD). A sort of relationship is defined between the CB and SD. [4][5][6][7] In the mouth breather patients, various jaw deformities such as narrow maxillary arch, posterior crossbite, more overjet, and a deep and dome-shaped palate are detected. [8] A deep and dome-shaped palate can induce stress on the nasal septum and cause septal deviation. [9] The effects of oral respiration from nasal blockage on dentofacial growth and development are indefinite. [10][11] Several studies have revealed that adenoid hypertrophy and chronic nasal blockage during early childhood period cause dentofacial deformity. [11][12] Oral respiration causes a higher palatal height. [13] This causes deviations in the posterior septum or it is exaggerated in the existing deviation. Akbay et al. detected an association between the height of the palate and posterior deviation of the nasal septum. The deviations had accelerated oral respiration and raised the depth of palatal bone. This phenomenon might increase SD in a blind circle. [8] This study is designed to determine the effects of septal deviation per se and in combination with concha bullosa on the maxilla and adjacent bones.

Materials and Method
In this descriptive-comparative study, 116 samples (71 males and 45 females) were selected from the archive of cone-beam computed tomography (CBCT) images of patients who referred to an oral and maxillofacial radiology clinic in North Iran during 2012-2014. The exclusion criteria were having less than 18 years of age, history of nasoantral mass, fractures of nasomaxillary complex, head and neck syndromes, and orthopedic or orthodontic treatments. All scans were made using a NewTom VG CBCT device (QR s.r.l., Verona, Italy) with a 9-inch field of view (FOV).
Based on the type of deviations detected, the enrolled samples were divided into four groups (n=29).  Table 1 summarizes the abbreviations of the above-used parameters. In this study, when DSCA was less than 150°, the septum was defined as a deviated form.
All data for this study were subjected to statistical analysis using SPSS (ver. 21; SPSS, Chicago, IL).
ANOVA was used for overall comparison among the groups and Tukey's HSD for pairwise comparison. Chisquare test was employed to compare the gender-based variables. The level of statistical significance was established at p≤ 0.05.    However, a positive correlation was found between PAD/PIL ratio and DSL (r=0.379, p= 0.043) ( Table 5).
In group 1, a linear correlation coefficient (R 2 =0.151) between the PAD/PIL ratio and DSCA revealed a 15% change in the PAD/PIL ratio as predicted and based on DSCA angle ( Figure 2).

Discussion
SD and CB are the most common anatomical variations.
They have been reported variously in different studies.
[3] The nasal septum affects the anterior-posterior growth of the maxilla and it was confirmed through stu-   dying the homozygous twins. [14] Obstructions of the  Drevenšek and Papić [16] found that patients with an incompetent lip had deeper palatal depth rather than those with a competent lip and adequate seal. Berwing et al. [1] concluded that mouth breathers had narrower and deeper palates in the posterior portion of palate.
Serter et al. [10] realized that the depth of maxillary arch was due to the flattened maxillary bone in the group with nasal polyposis. This was lesser than the control group. The results of our study were closer to the findings of Serter et al. [10] In the growth process of the maxillary bone, the palatal bone relocates downward. This relocation is caused by periosteal resorption in the nasal direction and periosteal deposition in the oral direction. [17] Therefore, any obstruction in the nasal airway such as SD and CB could affect the growth and downward remodeling of the palate.

Conclusion
PAD/PIL ratio had a negative correlation with the DSCA angle. This correlation is combined with a decrease in PAD. These findings suggest that simultaneous occurrence of SD and CB remarkably influences the depth and curve of the base of palate; however, this effect was not observed in the alveolar bone probably due to dental camouflage.